WO2022194589A1

WO2022194589A1 - Easy access via a partial lateral opening system

Info

Publication number: WO2022194589A1
Application number: PCT/EP2022/055700
Authority: WO
Inventors: Olivier GUIA; Luc Gaffet
Original assignee: L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Priority date: 2021-03-16
Filing date: 2022-03-07
Publication date: 2022-09-22
Also published as: EP4308864A1

Abstract

Refrigeration system (1) comprising: • -a first cryogenic chamber (10) defined by at least a first wall (11), the first cryogenic chamber (10) being thermally connected to at least a first cold source (41); • - second cryogenic chamber (50) defined by at least a second wall (51) which extends at least partially facing the first wall (11), the second chamber (50) being contained inside the first chamber (10) and thermally connected to at least a second cold source (43, 46); wherein the refrigeration system (1) comprises at least a first door (30) made in the first wall (11) substantially facing a second door (70) made in the second wall (51), the first door (30) and the second door (70) being arranged in such a way that the opening of the first door (30) allows the opening of the second door (70).

Description

Easy access by a partial side opening system

The present invention relates to the field of very low temperature refrigeration and more particularly to the field of refrigeration systems at temperatures of around one to a few kelvins, as well as refrigeration systems at temperatures below one kelvin, and in particular close to ten of millikelvin.

BACKGROUND OF THE INVENTION

Conventionally, a very low temperature refrigeration system comprises a first cryogenic enclosure defined by at least a first wall and a second cryogenic enclosure included inside the first enclosure and which is defined by at least a second wall which extends to the least partially facing the first wall. The first cryogenic enclosure is thermally connected to a first cold source and the second cryogenic enclosure is thermally connected to a second cold source.

Generally, the first wall and the second wall are cylindrical and similarly constructed. Thus, the first enclosure comprises two first half-cylinders assembled along a first longitudinal direction and the second enclosure comprises two second half-cylinders assembled along a second longitudinal direction, generally parallel to the first.

Access to the interior of the system and in particular to the coldest zone of the system when you need to carry out maintenance or when you want to install equipment to be cooled (for example a quantum chip, a sensor , a superconducting element, a scanning tunneling microscope (STM) or another object to be cooled), requires the removal of at least one of the first half-cylinders and one of the second half-cylinders. These operations use expensive lifting means to carry out risky handling of heavy elements. Such operations also involve a particularly long shutdown of the refrigeration system, which penalizes its operation.

Quantum computing is a relatively restrictive application currently under development. The emergence of the quantum computer, whose core operates in an environment characterized by low or very low temperatures, poses the problem of the generation and distribution of cold temperatures in an industrial architecture compatible with the operating constraints of a computing center. Here, low or very low temperatures are understood to mean temperatures potentially down to the range of temperatures from one milliKelvin to one hundred milliKelvin.

The use of refrigeration at temperatures below a hundred milliKelvin essentially concerns applications for the study of matter and quantum phenomena, for the production of electromagnetic radiation detectors.

Quantum phenomena give rise to theoretical and technological developments likely to implement them to perform operations ("quantum computing") for the development of supercomputers (performing for example a billion billion calculations per second) by manipulating "qubits » superconductors at temperatures close to a milliKelvin or based on silicon at a few hundred milliKelvin.

Generally, these applications use dilution refrigerators for cooling needs that allow them to manipulate a hundred qubits and integrate the hundreds of wired and coaxial links (about four per qubit) necessary to control them and read their state.

Thus, the traditional means of obtaining refrigeration power at temperatures in the range of miliKelvin to the hundred or several hundred miliKelvin is the helium3 and helium4 dilution refrigerator.

Other technologies offer cold powers of 8 to 30 microWatt at 20 mK or 250 to 1000 microWatt at 100 mK.

To eventually manipulate tens of thousands up to millions of qubits in a quantum computer, existing solutions are no longer suitable.

OBJECT OF THE INVENTION

The object of the invention is to reduce the costs and/or time of maintenance and/or installation of equipment to be cooled inside a low-temperature refrigeration system.

To this end, a refrigeration system is provided comprising a first cryogenic enclosure defined by at least one first wall, the first cryogenic enclosure being thermally connected to at least one first cold source. The system also comprises a second cryogenic enclosure defined by at least a second wall which extends at least partially opposite the first wall, the second enclosure being included inside the first enclosure and thermally connected to at least a second source cold. According to the invention, the refrigeration system comprises at least a first door made in the first wall substantially opposite a second door made in the second wall, the first door and the second door being arranged so that the opening of the first door allows the opening of the second door.

That is to say, the first door gives access to the second door.

Thus, the first door and the second door are arranged so that the opening of the doors allows the passage of an object from the exterior of the first enclosure to the interior of the second enclosure and vice versa.

A refrigeration system is thus obtained which allows easy and quick access to the interior of the second enclosure. The handling means are limited or even non-existent and the costs and time required to install a device to be cooled in the second enclosure are reduced.

It is also possible to intervene easily for a maintenance operation inside the first enclosure (by opening only the first door) or inside the second enclosure (by opening the first and of the second door).

Advantageously, the first door comprises a first frame on which a first panel is removably mounted, and in which the second door comprises a second frame on which a second panel is removably mounted.

Advantageously, the first enclosure and/or the second enclosure is a cylinder whose directing curve is polygonal, preferably octagonal, the panels being flat.

The production of the enclosures is simplified when the first panel defines a first side face of the first enclosure, the first panel being of quadrangular shape and comprising a first width corresponding to a length of a segment of the directing curve and a first height which is extends parallel to a generatrix of the cylinder.

Optionally, the system comprises a third door made in the first wall and a fourth door made in the second wall substantially opposite the third door.

The times and costs for installing a device in the second enclosure are further reduced when the first and second doors belong to a first airlock and the third and fourth doors belong to a second airlock, the first airlock and the second airlock being arranged to provide autonomous and independent access from the exterior of the first enclosure to the interior of the second enclosure respectively to a first module and a second module which both comprise a slot configured to receive at least one quantum chip, a sensor, a superconducting element, scanning tunneling microscope (STM) or other object to be cooled. When an airlock is present, loading and unloading can therefore be done without stopping the operation of the system.

The thermal insulation of the enclosures is improved when the first wall and/or the second wall comprises a material blocking the passage of infrared rays.

The time and cost of installing a device in the second enclosure is further reduced when the system comprises members for mechanically connecting the first door with the second door.

Advantageously, the first door and/or the second door comprises a support for receiving an element to be cooled.

The construction of the system is simplified and the procedures for accessing the doors easier when the first cryogenic enclosure comprises a first end face through which extends a first heat transfer element of the first cold source and/or the second cryogenic enclosure comprises a second end face through which extends a second heat transfer element of the second cold source.

According to a preferred embodiment, the first wall comprises a first cylindrical structure with a polygonal base on which are attached a plurality of first panels, at least one first panel being removably mounted on the first structure to constitute the first door and/or the second wall comprises a second cylindrical structure with a polygonal base on which are attached a plurality of second quadrangular plates, at least one second plate being removably mounted on the second structure to form the second door.

Optionally, in the case where the cylinders have a polygonal directing curve, each face of the first and second walls can be removable and constitute a door.

The thermal losses of the system are reduced when the first cryogenic enclosure is included in a first external enclosure or even when the first external enclosure is included in a second external enclosure.

The first outer enclosure may include a third door and the second outer enclosure may include a fourth door, these doors being substantially opposite each other, as well as first and second doors. The first and the second external enclosure can be cylinders with an octagonal base, of which at least one of the faces (or all the faces) constitutes an access door.

Advantageously, the first cold source is configured to maintain a temperature comprised between 2.5 Kelvins and 5 Kelvins, preferably substantially equal to 4 Kelvins, inside the first enclosure, and the second cold source is configured to maintain a temperature comprised between 0.6 Kelvins and 1.5 Kelvins inside the second enclosure.

Advantageously, the first external enclosure is thermally connected to a third cold source, preferably configured to maintain a temperature of between forty Kelvins and one hundred Kelvins inside the first additional enclosure.

According to an embodiment particularly well suited to quantum computing, the subject of the present invention is a refrigeration system for receiving independent modules comprising quantum chips operating at very low temperatures, comprising:

- a first cryogenic enclosure thermally connected to at least a first cold source, the first cryogenic enclosure and the first cold source being configured to make it possible to maintain a temperature less than or equal to 150 K inside the first cryogenic enclosure,

- a second cryogenic enclosure included inside the first cryogenic enclosure and thermally connected to at least one second cold source, the second cryogenic enclosure and the second cold source being configured to make it possible to maintain a temperature less than or equal to 6 K at inside the second cryogenic chamber,

- a plurality of independent thermal locks each allowing autonomous and independent access from the outside of the first cryogenic enclosure to the interior of the second cryogenic enclosure of a module comprising quantum chips.

For the purposes of the present invention, and in accordance with the definition given by the Larousse dictionary available online (2021 - https://www.larousse.fr/dictionnaires/francais/sas/71049), the term "sas" designates an enclosure or closed passage, equipped with two doors or closing systems, one of which can only be opened if the other is closed and which allows passage or passage from one environment to another while maintaining these isolated from each other.

The invention proposes the implementation of a chaining of temperatures from ambient temperature to a temperature below 6K which allows energy efficiency. The presence of independent thermal locks allows flexibility of use of the system. In particular, it is possible to act on part of the modules comprising quantum chips without affecting the other modules comprising quantum chips.

The system according to the invention allows the passage to the industrial scale where it is no longer a question of cooling a few cm ² to 15 mK but of proposing an industrial solution allowing to cool a much larger surface of the order of 1 m ² to several m ² .

The use of the first and second cryogenic chambers makes it possible to obtain an environment at a temperature less than or equal to 6K that can independently accommodate several modules carrying quantum chips and possibly one or more sub-Kelvin refrigeration devices. This makes it possible to offer an industrial solution to the development of quantum computers.

The refrigeration system according to the invention may also include one or more of the following characteristics considered individually or in all possible combinations:

the first cryogenic chamber is thermally connected to the first cold source by a circuit capable of transferring cold power from said first cold source to said first cryogenic chamber; and or
the second cryogenic chamber is thermally connected to the second cold source by a circuit capable of transferring cold power from said second cold source to said second cryogenic chamber; and or
the first cryogenic enclosure is included in an outer enclosure sealed at ambient temperature; and or
all the enclosures sharing the same pressure less than or equal to 10 -4 mbar and greater than or equal to 10 -7 mbar and the thermal locks each allowing autonomous and independent access from outside the outer enclosure; and or
the system comprises a third cryogenic enclosure included inside the second cryogenic enclosure and thermally connected to at least a third cold source, the third cryogenic enclosure and the third cold source being configured to make it possible to maintain a temperature lower than or equal to 2 K inside the third cryogenic enclosure, and at least part of the thermal locks allow autonomous and independent access from outside the first cryogenic enclosure to the interior of the third cryogenic enclosure of a module comprising chips quantum; and or
the third cryogenic chamber is thermally connected to the third cold source by a circuit capable of transferring cold power from said third cold source to said third cryogenic chamber; and or
the thermal locks are configured to receive from outside one of the cryogenic enclosures modules comprising quantum chips and the links allowing communication with said quantum chips; and or
wherein the thermal locks are configured to receive from outside the outer enclosure modules comprising quantum chips and the links for communicating with said quantum chips; and or
the refrigeration system further includes inter-module links for interconnecting quantum chips of different modules; and or
the refrigeration system further comprises an anti-radioactivity protection device around at least one of the first and/or second and/or third cryogenic chambers, the anti-radioactivity protection device being configured to protect the interior of the system external radiation refrigeration; and or
the devices and materials used inside the anti-radioactivity protection device are selected and manufactured in order to control the level of radioactivity inside the anti-radioactivity protection device; and or
the refrigeration system includes a plurality of sub-Kelvin refrigeration devices disposed at least in part in the second cryogenic chamber, each refrigeration device being configured to produce cold power so as to allow a lower temperature to be obtained or equal to 1K, in particular less than or equal to one hundred milliKelvin; and or
at least one of the independent thermal airlocks allows access to a module including quantum chips from outside the first cryogenic chamber to at least one of the sub-Kelvin refrigeration devices; and or
at least a part of the sub-Kelvin refrigeration devices are arranged in the third cryogenic vessel; and or
the refrigeration system comprises at least one module and at least one refrigeration device, said at least one module comprising quantum chips, said at least one refrigeration device being configured to produce cold power so as to allow obtaining a temperature less than or equal to 1K, in particular less than or equal to a hundred milliKelvin, and at least one thermal lock allowing access to said at least one module from outside the first cryogenic enclosure inside the second cryogenic chamber; and or
the refrigeration system comprises at least one module, said at least one module comprising quantum chips and at least one refrigeration device, said refrigeration device being configured to produce cold power so as to allow a temperature to be obtained less than or equal to 1K, in particular less than or equal to a hundred milliKelvin, and at least one thermal lock allowing access to said at least one module from outside the first cryogenic enclosure inside the second cryogenic enclosure; and or
at least one of the sub-Kelvin refrigeration devices is a 3 He refrigeration device; and or
at least one of the sub-Kelvin refrigeration devices is an adiabatic demagnetization refrigeration device; and or
at least one of the sub-Kelvin refrigeration devices is a dilution refrigeration device; and or
the sub-Kelvin refrigeration device includes at least one cryogenic pumping member located in its working circuit; and or
at least two of the sub-Kelvin refrigeration devices are like-kind refrigeration devices and share a single cryogenic pumping member; and or
the cryogenic pumping device is located inside the first cryogenic chamber and outside the second cryogenic chamber; and or
the cryogenic pumping device is located inside the second cryogenic chamber and outside the third cryogenic chamber; and or
the cryogenic pumping unit is located inside the third cryogenic enclosure; and or
which the sub-Kelvin refrigeration device is inside the third cryogenic chamber; and or
each sub-Kelvin refrigeration device is configured to operate at different sub-Kelvin temperatures.

Other characteristics and advantages of the invention will become apparent on reading the following description of particular and non-limiting embodiments of the invention.

Reference will be made to the accompanying drawings, among which:

the is a schematic cross-sectional view of a refrigeration system according to a first embodiment of the invention;

the is a schematic perspective view of the refrigeration system of the ;

the is a schematic exploded perspective view of a first enclosure of the refrigeration system of the ;

the is a sectional detail view of an upright of the enclosure of the ;

the is a schematic exploded perspective view of a second enclosure of the refrigeration system of the ;

the is a schematic view in longitudinal section of a refrigeration system according to a second embodiment of the invention;

the is a schematic view in longitudinal section of a refrigeration system according to a third embodiment of the invention; the is a perspective detail view of a refrigeration system according to a fourth embodiment of the invention;

the is a perspective detail view of a refrigeration system according to a fifth embodiment of the invention;

the is a schematic cross-sectional view of a refrigeration system according to a sixth embodiment of the invention;

the is a schematic view in longitudinal section of a refrigeration system according to a seventh embodiment of the invention;

the is a schematic cross-sectional view of a refrigeration system according to an eighth embodiment of the invention.

the is a schematic view in longitudinal section of a refrigeration system according to a ninth embodiment of the invention;

the is a schematic perspective view of a second outer enclosure according to a tenth embodiment of the invention;

the is a schematic perspective view of a second outer enclosure according to an eleventh embodiment of the invention.

the is a schematic representation of a refrigeration system according to a twelfth embodiment of the invention in application to quantum computing,

the is a schematic representation of a refrigeration system according to a thirteenth embodiment of the invention,

the is a schematic representation of a refrigeration system according to a fourteenth embodiment of the invention, and

the is a schematic and partial representation illustrating an example of a sub-Kelvin refrigeration device structure that can be used in a refrigeration system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures 1 to 5, the refrigeration system according to the invention, and generally designated 1, comprises a first cryogenic enclosure 10 defined by a first wall 11. When the refrigeration system is running (active) the enclosure 10 is preferably under vacuum, that is to say at a pressure of less than one ten thousandth of a millibar. The system 1 also comprises a second cryogenic enclosure 50 defined by a second wall 51 which extends opposite the first wall 11. Similarly, in operation the enclosure 50 is preferably under vacuum, that is to say at a pressure less than one ten thousandth of a millibar. As seen in , the enclosure 50 is included inside the enclosure 10. The

walls

11 and 51 are separated from each other by a non-zero distance. The two

enclosures

10 and 50 preferably share the same vacuum atmosphere.

The enclosure 10 is here a cylinder with a first longitudinal axis O10 whose first directing curve 12 is octagonal. Here, curve 12 defines a regular octagon. More specifically, the enclosure 10 includes a first mechanically welded frame 13. The frame 13 comprises a first lower octagonal base 14 shown resting on a horizontal plane Ph according to the representations of Figures 2, 3 and 5. The base 14 is made using sections of metal angle iron assembled by welding which constitute eight first segments 14.1 to 14.8 connecting the first eight vertices 15.1 to 15.8 of the base 14 and thus define a regular octagon.

Frame 13 also comprises a second upper base 16 identical to base 14 and which comprises eight second vertices 17.1 to 17.8 interconnected by second segments 18.1 to 18.8.

The vertices 15.1 to 15.8 are respectively connected to the vertices 17.1 to 17.8 by eight identical first uprights 19.1 to 19.8. As seen in , the first upright 19.1 comprises a pentagon-shaped section 19.10 and has two adjacent outer edges 19.11 and 19.12 spaced apart by an angle α substantially equal to one hundred and thirty-five degrees. Similarly, the amount 19.2 has two outer edges 19.21 and 19.22, the amount 19.3 has two outer edges 19.31 and 19.32, the amount 19.4 has two outer edges 19.41 and 19.42, the amount 19.5 has two outer edges 19.51 and 19.52, the amount 19.6 has two outer edges 19.61 and 19.62, amount 19.7 has two outer edges 19.71 and 19.72, amount 19.8 has two outer edges 19.81 and 19.82.

Frame 13 thus defines eight rectangular frames:

a frame 20 delimited by the segments 14.1 and 18.1 as well as by the edges 19.11 and 19.22;
a frame 21 delimited by the segments 14.2 and 18.2 as well as by the edges 19.21 and 19.32;
a frame 22 delimited by the segments 14.3 and 18.3 as well as by the edges 19.31 and 19.42;
a frame 23 delimited by the segments 14.4 and 18.4 as well as by the edges 19.41 and 19.52;
a frame 24 delimited by the segments 14.5 and 18.5 as well as by the edges 19.51 and 19.62;
a frame 25 delimited by the segments 14.6 and 18.6 as well as by the edges 19.61 and 19.72;
a frame 26 delimited by the segments 14.7 and 18.7 as well as by the edges 19.71 and 19.82;
a frame 27 delimited by the segments 14.8 and 18.8 as well as by the edges 19.81 and 19.12.

The enclosure 10 comprises eight panels 30 to 37 planes respectively reported by bolting on the frames 20 to 27 to define eight first side faces of the enclosure 10. The panels 30 to 37 are here rectangular in shape and all include a first width l1 corresponding to a length of a segment 14.1 to 14.8 and a first height H1 which extends parallel to a generatrix of the enclosure 10. Here, the height H1 is equal to the length of the uprights 19.1 to 19.8. Panels 30-37 are preferably made of an infrared blocking material such as copper.

The enclosure 10 comprises a lower end face 38 fixed on an edge of the base 14 and an upper end face 39 fixed on an edge of the base 16. The face 39 includes the connections to the auxiliary equipment. Face 39 is connected via a braid 40 to a first cold source, here the second stage 41 of a pulsed tube, not shown, which thermalizes enclosure 10.

The face 39 also comprises a first passage 39.1 of a pipe 42 connected to a first circulator or pump 43, a second passage 39.2 of a pipe 44 also connected to the circulator or pump 43 and a third passage 39.3 of a pipe 45 connected to a second pump 46. The circulator or pump 43 circulates a mixture of Helium 3 and Helium 4 in a set of tanks and pipes located inside the enclosure 50 to constitute a He3 dilution refrigerator /He4. The cold source 41 is configured to maintain a temperature of between 1.5 Kelvins and 5 Kelvins, preferably substantially equal to four Kelvins, inside the enclosure 10. The dilution refrigerator supplied by the circulator or pump 43 is configured to maintain a temperature between 0.6 Kelvin and 1.5 Kelvin inside the enclosure 50. The pump 46 is configured to maintain a pressure less than or equal to one ten-thousandth of a millibar in the enclosure 10 In this example, enclosure 10 is sealed, while enclosure 50 is not and shares the same vacuum as enclosure 10.

The enclosure 50 has a structure identical to that of the enclosure 10 and can be assimilated to a reduced image of the enclosure 10 whose reduction factor along the axis O10 would be greater than the reduction factor along an axis orthogonal to the axis O10. Enclosure 10 is taller than enclosure 50 and encloses enclosure 50.

As seen in , the enclosure 50 is a cylinder with a longitudinal axis O10 whose second directing curve 52 is octagonal. Here, curve 52 defines a regular octagon. The enclosure 50 comprises a frame 53 comprising a third octagonal lower base 54 whose vertices 55 are connected to vertices 56 of a fourth octagonal upper base 57 by uprights 58. The chassis 53 thus defines eight rectangular frames 60 to 67 on which are respectively attached by bolting eight panels 70 to 77 planes to define eight second side faces of the enclosure 50. The panels 70 to 77 extend respectively opposite the panels 30 to 37 and are preferably made of a material blocking infrared such as copper. The panels 70 to 77 are here rectangular in shape and have a second height H2 which extends parallel to a generatrix of the cylinder. Here, the height H2 is equal to the length of the uprights 58. The panels 70 to 77 have a second width l2 substantially equal to the distance separating two adjacent vertices 55. The enclosure 50 comprises an upper end face 59 on an edge of the base 57 which comprises a fourth passage 59.1 of the pipe 42 and a fifth passage 59.2 of the pipe 44 so as to connect the circulator or pump 43 to the He3/He4 dilution refrigerator located inside enclosure 50.

The panel 30 forms a first panel which forms a first door in the first wall 11 of the first enclosure 10. The frame 20 forms a first frame on which the first panel 30 is mounted.

The panel 70 forms a second panel which forms a second door in the second wall 51 of the second enclosure 50. The frame 60 forms a second frame on which the second panel 70 is mounted.

The end face 39 is, here, a first end face and the end face 59 is, here, a second end face.

The second door is thus substantially opposite the first door.

The panel 31 forms a third panel which forms a third door in the first wall 11 of the first enclosure 10. The frame 21 forms a third frame on which the third panel 31 is mounted.

The panel 71 forms a fourth panel which forms a fourth door in the second wall 51 of the second enclosure 50. The frame 61 forms a fourth frame on which the fourth panel 71 is mounted.

The fourth gate is thus substantially opposite the third gate.

The sealing elements that may be necessary to seal the enclosures are known per se and are not described here.

In operation, when it is desired to install a device to be cooled in the enclosure 50 or to intervene for maintenance, the system is shut down, then the enclosure 10 is vented using of the pump 46. Then the panel 30 is unbolted from the frame 20 and removed. Once the panel 30 has been removed, the panel 70 is accessible by working through the frame 20. The panel 70 is then unbolted and removed from the frame 60. The interior of the enclosure 50 is then accessible and the device cooling can be easily installed there and connected, if necessary, to various connections, or maintenance can be carried out in an easy manner.

Panels

30 and 70 are then reassembled on

frames

20 and 60 respectively. thermalize the enclosure 10 and the circulator or pump 43 is actuated to start the He3/He4 dilution refrigerator.

Elements similar or analogous to those previously described will bear a numerical reference identical to these in the following description of the second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth and eleventh embodiments of the invention.

According to a second embodiment shown in , the system 1 comprises a first tube 80 and a second tube 90 diametrically opposed with respect to the axis O10 and which are both welded to the

walls

11 and 51. The first tube 80 comprises a first end 81 which projects from the wall 11 outside the enclosure 10. The end 81 comprises a flange 82 on which is bolted a closing plate 83. The plate 83 comprises a gas-tight thread 84 in which a threaded plunger 85 is engaged. The second end 86 of the tube 80 projects inside the enclosure 50 and comprises a closure flap 87 returned to the closed position using a spring hinge 88. End 86 forms a support frame for shutter 87.

The tube 90 is identical to the tube 80 and comprises, at its end 91 which projects from the outside of the enclosure 10, a flange 92 on which is bolted a closure plate 93. A threaded plunger 95 is engaged in a thread 94 of the plate 93. The end 96 of the tube 90 opposite the end 91 comprises a closing flap 97 pivotally mounted using a spring hinge 98. End 96 forms a support frame for shutter 97.

The tube 80 constitutes a first airlock 89 which comprises a first door (the plate 83) made in the wall 11 and a second door (the shutter 87) made in the wall 51.

The tube 90 constitutes a second airlock 99 which comprises a third door (the plate 93) made in the wall 11 and a fourth door (the shutter 97) made in the wall 51.

In operation, when it is desired to install a device to be cooled in the enclosure 50, here a first module 100 comprising a first quantum chip 101 provided with pins 102, the plate 83 is deposited and the module 100 is introduced into the tube 80 Plate 83 is put back in place and bolted. The volume of the airlock 89 is then placed under vacuum then the module 100 is thermalized to the temperature of the enclosure 50. The pusher 85 is then acted upon so as to advance the module 100 inside the tube 80 in the direction of the enclosure 50 until the module 100 comes into contact with the flap 87. By again acting on the pusher 85, the flap 87 is opened and the module 100 is introduced into the enclosure 50. The flap 87 is closed after the loading of the module 100 in the enclosure 50. The module 100 can be connected to an instrumentation 200 via a port 201 of the enclosure 50.

The airlock 99 functions identically to the airlock 89 for the introduction of a second module 103 comprising a second quantum chip 104.

A refrigeration system 1 is thus obtained comprising a first airlock 89 and a second airlock 99 arranged to provide autonomous and independent access to the interior of the enclosure 50 from the exterior of the enclosure 10 respectively to the first module 100 and to a second module 103. Indeed, in this embodiment, no operation of emptying the enclosure 10 or stopping the He3/He4 dilution refrigerator is necessary to be able to introduce a

module

100 or 103 into the enclosure 50 from outside enclosure 10. According to a third embodiment shown in , the plate 83 is bolted directly to the wall 11 and no sealed connection is made between the plate 83 and the shutter 87 (no tube 80). Plate 83 is devoid of thread 84 in order to maintain tight closure of wall 11 by plate 83. Similarly, plate 93 is bolted directly to wall 11 and no tight connection is made between plate 93 and flap 97 (no tube 90). The plate 93 is devoid of the thread 94 in order to maintain a sealed closure of the wall 11 by the plate 93.

According to a fourth embodiment shown in , the panel 30 is connected to the panel 70 by a set of four spring jacks 110 made of fiberglass in order to limit thermal conduction. Each cylinder 110 comprises a rod 111 slidably mounted in a sleeve 112 and on which a spring 113 exerts a thrust force in a direction going from the panel 30 towards the panel 70.

Panel 30 is attached to frame 20 by bolting. Panel 70 is held in place on frame 60 by the thrust force exerted by rods 111 on panel 70.

Thus, the removal of the panel 30, which corresponds to the opening of the first door made in the wall 11, allows the opening of the second door, namely the removal of the panel 70.

According to a fifth embodiment shown in , the system 1 comprises a first shelf 120 which projects from the panel 30 towards the inside of the enclosure 10. A second shelf 121 extends from the panel 70 towards the inside of the enclosure 50.

Shelves

120 and 121 are used as support for receiving an element which it is desired to bring to low temperature (of the order of one kelvin for the shelf 121 and of the order of four kelvins for the shelf 120) .

According to a sixth embodiment shown in , the enclosure 10 is included in a first external enclosure 130 which forms a screen at fifty Kelvins. The enclosure 130 is here of cylindrical shape composed of two bolted half-cylinders and is thermally connected using a conductive braid 47 to the first stage 48 of a pulsed tube, not shown. The first stage 48 is configured to maintain a temperature between forty Kelvins and one hundred Kelvins inside the enclosure 130.

The enclosure 130 is also included in a second external enclosure 140 which produces a screen at ambient temperature (typically of the order of three hundred Kelvin). The enclosure 140 is here of cylindrical shape composed of two bolted half-

cylinders

141 and 142. When the first outer enclosure 130 and/or the second outer enclosure 140 are present, the pump 43 and the pump 46 are preferably positioned outside speaker. The pump 43 is then connected inside the second enclosure 50 by the

pipes

42, 44. The pump 46 is configured to maintain a pressure below one ten thousandth of a millibar inside the device 1.

According to a seventh embodiment shown in , the enclosure 130 has a structure identical to that of the enclosure 50. The enclosure 130 is thus a cylinder with a longitudinal axis O10 and a third wall 131 whose third directing curve 132 is octagonal. The enclosure 130 comprises a frame 133 comprising a fifth octagonal lower base whose vertices are connected to vertices of a sixth octagonal upper base by uprights 138.1 to 138.8. The frame 133 thus defines eight rectangular frames 150 to 157 on which are respectively attached by bolting eight panels 160 to 167 planes to define eight third side faces of the enclosure 130. The panels 160 to 167 extend respectively opposite the panels 70 at 77.

The panel 160 forms a fifth panel which forms a fifth door (or a first additional door) in the third wall 131 of the enclosure 130. The panel 160 is thus substantially opposite the panel 70 and the fifth door (the first additional door ) is thus substantially opposite the fourth gate.

Thus, when it is desired to install a device to be cooled in the enclosure 50 or to intervene for maintenance, the system 1 is shut down, then the enclosure 10 is vented using of the pump 46. The half-cylinder 142 is removed to access the interior of the enclosure 140. The panel 160 is unbolted from the frame 150 and removed. The panel 160 removed, the panel 30 is accessible by intervening through the frame 150 and the panel 30 is unbolted from the frame 20 and removed. Once panel 30 has been removed, panel 70 is accessible by working through frame 20. Panel 70 is then unbolted and removed from frame 60. The interior of enclosure 50 is then accessible. Thus, the opening of the fifth door (first additional door) allows the opening of the first door.

Advantageously, and according to an eighth embodiment shown in , the enclosure 140 comprises a sixth door 143 (or second additional door) made in the form of a sixth panel bolted to the half-cylinder 142 to hide a cutout 144.

The cutout 144 is substantially opposite the panel 160. Thus, the removal of the door 143 allows access to the panel 160 by intervening through the opening 143 and allows the opening of the sixth door.

According to a ninth embodiment shown in , the enclosure 140 has a structure identical to that of the enclosure 130. The enclosure 140 is thus a cylinder with a longitudinal axis O10 and a fourth wall 145 whose fourth directing curve 146 is octagonal. The enclosure 140 comprises a frame 147 comprising a fifth octagonal lower base whose vertices are connected to vertices of a sixth octagonal upper base by uprights 148.1 to 148.8. The chassis 147 thus defines eight rectangular frames 170 to 177 on which are respectively attached by bolting eight panels 180 to 187 planes to define eight fourth side faces of the enclosure 140. The panels 180 to 187 extend respectively opposite the panels 160 at 167.

The panel 180 forms a sixth panel which forms a sixth door in the fourth wall 145 of the enclosure 140. The panel 180 is thus substantially facing the panel 160 and the sixth door is thus substantially facing the fifth door.

Thus, when it is desired to install a device to be cooled in the enclosure 50 or to intervene for maintenance, the system 1 is shut down, then the enclosure 10 is vented using of the pump 46. The panel 180 is unbolted from the frame 170 and removed. The panel 180 removed, the panel 160 is accessible by intervening through the frame 170 and the panel 160 is unbolted from the frame 150 and removed. Panel 160 removed, panel 30 is accessible by working through frame 150. Panel 30 is then unbolted and removed from frame 20. Panel 30 removed, panel 70 is accessible by working through the frame 20. The panel 70 is then unbolted and removed from the frame 60. The interior of the enclosure 50 is then accessible.

According to a tenth embodiment shown in , the second outer enclosure 140 is, here, a one-piece cylinder 180 which is mounted around the first outer enclosure 130 by translation parallel to the axis O10. A first lower cover 181 and a second upper cover 182 are attached by bolting respectively to the lower end 183 and the upper end 184 of the cylinder 180. The cover 182 is configured to allow the necessary connections to pass, preferably in a sealed manner. For example, the cover 182 comprises leaktight passage holes for cables and/or other equipment.

According to an eleventh embodiment shown in , the cylinder 180 comprises an upper cylinder portion 185 attached/fixed in leaktight manner, for example by bolting, to a lower cylinder portion 186.

Will now be described the twelfth, thirteenth and fourteenth embodiments of the invention, more particularly adapted to integrate a quantum computing system.

As shown on the , the invention relates to a refrigeration system 210 configured to receive independent modules 220 comprising quantum chips 222 operating at very low temperatures.

Within the meaning of the invention, a very low temperature is a temperature less than or equal to 1.8 K, preferably less than or equal to 800 mK, preferably less than or equal to 100 mK and greater than or equal to 2 mK.

Within the meaning of the invention, a quantum chip corresponds to an electronic system making it possible to produce qubits. A cold source may comprise at least one of: a cryogenic fluid bath, for example a liquid helium bath, a liquid nitrogen bath, a superfluid helium bath, a cryogenerator or cryocooler ("cryocooler" in English), a cycle gas refrigerator, or any other apparatus or system making it possible to produce cold in particular at cryogenic temperatures, for example below -150°C.

The refrigeration system according to the invention is not limited to receiving modules comprising quantum chips, but can receive sensors, for example bolometers, which require very low temperatures.

As shown on the , a refrigeration system 210 according to the invention comprises at least:

a first cryogenic chamber 230,
a second cryogenic enclosure 240, and
a plurality of independent thermal locks 250.

The first cryogenic enclosure 230 is thermally connected to at least a first cold source 232. The first cryogenic enclosure 230 and the first cold source 232 are configured to make it possible to maintain a temperature less than or equal to 150 K, preferably less than or equal to 77 K and greater than or equal to 50K, inside the first cryogenic enclosure.

Typically, the first cryogenic enclosure 230 is thermally connected to the first cold source 232 by a circuit 234 capable of transferring cold power from the first cold source 232 to the first cryogenic enclosure 230. The heat transfer between the first cold source 232 and the first cryogenic chamber 230 can be produced by direct heat exchange or by indirect heat exchange. For example, a heat transfer fluid cooled by the cold source is circulated in direct or indirect contact with the wall of the containment. Alternatively or cumulatively, the wall of the enclosure could be connected to a cold source by a heat-conducting mechanical connection (for example a braid or a copper bar). Any other appropriate heat transfer mode can be considered.

According to a preferred embodiment of the invention, the first cold source 232 is based on liquid nitrogen or any other coolant and makes it possible to supply a cold power of the order of 100 W per MW for a temperature of 50 K and 150 K. For example, a cryogenic fluid from the first cold source (nitrogen or other or mixture) is circulated in heat exchange with an exchanger or a heat exchange member connected to the walls of the first enclosure, or by exchange thermal gas with the volume of the first enclosure.

The second cryogenic enclosure 240 is inside the first cryogenic enclosure 230. In addition, the second cryogenic enclosure is thermally connected to at least one second cold source 242. For example, as mentioned above, a heat transfer fluid cooled by the cold source is circulated in direct or indirect contact with the wall of the enclosure. Alternatively or cumulatively, the wall of the enclosure could be connected to a cold source by a mechanical connection (for example a braid or a copper bar). The second cryogenic chamber 240 and the second cold source 242 are configured to make it possible to maintain a temperature less than or equal to 6 K, for example less than or equal to 5 K, and greater than or equal to 2.8 K inside the second cryogenic enclosure.

Typically, the second cryogenic enclosure 240 is thermally connected to the second cold source 242 by a circuit 244 capable of transferring cold power from the second cold source 242 to the second cryogenic enclosure 240. The heat transfer between the second cold source 242 and the second cryogenic enclosure 240 can be produced by direct heat exchange or by indirect heat exchange.

According to a preferred embodiment of the invention, the second cold source 242 is based on liquid helium and makes it possible to supply a cold power of the order of 10 W to 100 kW for a temperature comprised between 2.8 K and 6 K. The second cold source 242 is for example a refrigerator subjecting a cycle gas (such as helium or hydrogen or any suitable mixture) to a thermodynamic cycle to produce cold at one end.

Preferably, the second cold source 242 can be arranged outside the first cryogenic enclosure and supplies cold to the second enclosure via the circuit 244. Alternatively, the second cold source 242 can be arranged in the first cryogenic enclosure.

The refrigeration system according to the invention also comprises a plurality of independent thermal locks 250. Each thermal airlock allows autonomous and independent access from the outside of the first cryogenic enclosure to the interior of the second cryogenic enclosure of a module 220. For example, each airlock comprises two doors and is movable between a sealed closed position allowing the cooling of the module and an open position ensuring the loading and/or the unloading of the module in the system. The module 220 comprises for example quantum chips 222 making it possible to produce qubits.

Each heat lock 250 allows the module to have an interface external to the first cryogenic enclosure, typically at room temperature, comprising electrical and/or electronic and/or fluidic connections making it possible to respectively connect the electrical and/or electronic and/or fluids of the module, for example the supply of fluids to a sub-K refrigerator integrated in the module 220.

In order to ensure independent operation of each thermal lock 250, each thermal lock has a roughing device, an opening allowing the insertion of a module 220, fluidic and/or thermal connections allowing thermal links to be established with all the cold parts.

Advantageously, each module can thus be managed independently, in particular, it is possible to intervene on one of the modules without affecting the other modules.

According to one embodiment of the invention, at least a part, for example all, of the thermal locks are configured to receive from the outside of one of the cryogenic enclosures modules comprising quantum chips and the connections making it possible to communicate with said quantum chips. Communication with quantum chips can include driving said chips individually, reading and changing the state of each quantum chip individually.

The refrigeration system according to the invention may also comprise a system of inter-module links making it possible to communicate between them quantum chips of different modules, for example to communicate between them quantum chips of the same nature or of different natures ( for example superconducting or Josephson effect quantum chips and CMOS quantum chips). Advantageously, this can allow communication between chips of different modules. The connection system can for example comprise electrical or electronic connections, or connections by electromagnetic waves (for example microwaves or light), or any other suitable communication method.

In order to ensure optimum operation, the system according to the invention is preferably at very low pressure. Typically the pressure inside the system according to the invention is less than or equal to 10 ^-4 mbar, for example less than or equal to 10 ^-5 mbar, preferably less than or equal to 10 ^-6 mbar and greater than or equal to 10 ^-7 mbar.

As shown on the , according to one embodiment of the invention, the refrigeration system according to the invention may comprise an external enclosure 260 at ambient temperature, that is to say in contact with the ambient atmosphere surrounding the system, for example in an installation in a temperate country this temperature could be between 0°C and 40°C.

Advantageously, the outer enclosure 260 is sealed and allows the system according to the invention to be placed under vacuum. Typically, the first cryogenic enclosure 230 is included in the outer enclosure 260. In this case, the first cryogenic enclosure 30 may not be sealed. The outer enclosure 260 can be connected to at least one vacuum pump 262 which allows all the enclosures included in the outer enclosure 260 to share the same pressure less than or equal to 10 ^-4 mbar, for example less than or equal to 10 ^-5 mbar, preferably less than or equal to 10 ^-6 mbar and greater than or equal to 10 ^-7 mbar.

According to an alternative embodiment, the different enclosures of the system according to the invention can have different vacuum levels, for example if it is desired to insert an exchange gas inside a single enclosure. In this case, the internal enclosures can be sealed and an airlock can be provided between each enclosure. According to such an embodiment, the system includes valves and pipes to manage the vacuuming and pumping.

In the embodiment comprising an external enclosure 260, the thermal locks 250 are configured to each allow autonomous and independent access from outside the external enclosure 260.

Likewise, in the mode comprising an external enclosure 260, the thermal locks 250 are preferably configured to receive from outside the external enclosure modules comprising quantum chips and the links making it possible to communicate with said quantum chips.

Quantum chips can be very sensitive to external radiation, in particular their operation can be altered by this radiation, in particular by cosmic radiation. It may therefore be advantageous to make it possible to protect quantum chips from this type of radiation, in particular when they are placed inside the refrigeration system according to the invention.

Thus, according to one embodiment of the invention, the refrigeration system further comprises an anti-radioactivity protection device around at least one of the first and/or second cryogenic enclosures and/or external enclosure, the anti-radioactivity protection being configured to protect the interior of the refrigeration system from external radiation. For example, it is possible to use a lead shield around quantum chips to protect them from outside radiation.

Preferably, the materials used inside the anti-radioactivity protection device are selected and manufactured in order to control the level of radioactivity inside the anti-radioactivity protection device. For example, the lead used around quantum chips may be archaeological lead, which has very low intrinsic radioactivity.

According to an embodiment of the invention shown in , in addition to the enclosures and cold sources described in connection with the embodiment of the , the refrigeration system according to the invention may also comprise a third cryogenic chamber 270.

The third cryogenic enclosure 270 is included inside the second cryogenic enclosure 240 and thermally connected to at least one third cold source 272. For example, a heat transfer fluid cooled by the cold source is circulated in direct or indirect contact with the enclosure wall. Alternatively, the wall of the enclosure could be connected to a cold source by a thermally conductive mechanical connection, for example a braid or a copper bar. The third cryogenic chamber 270 and the third cold source 272 are configured to make it possible to maintain a temperature less than or equal to 3 K, preferably less than or equal to 2 K, and greater than or equal to 1.8 K inside the third cryogenic enclosure.

The heat transfer between the third cold source 272 and the third cryogenic chamber 270 can be achieved by a direct heat exchange or by an indirect heat exchange. For example, a cryogenic fluid from the third cold source (for example helium) is circulated in heat exchange with an exchanger or a heat exchange member connected to the walls of the third enclosure, or by gaseous heat exchange with the volume of the third speaker.

According to a preferred embodiment of the invention, the third cold source 272 is for example based on liquid helium and makes it possible to supply a cold power comprised between around 100W and around 10kW around 2K, for example a cold power between 100W and 7.2kW, or cold power between 100W and 5kW can be supplied in the 1.6K-2.2K range.

Typically the third cold source is a helium refrigerator capable of lowering the temperature of the helium to 2 K or even 1.8 K by pumping on a refrigerated helium bath obtained by subjecting the helium (or other fluid or mixture) to a thermodynamic cycle producing cold at one end.

Preferably, the third cold source 272 can be arranged outside the first cryogenic enclosure, or even outside the external enclosure, and supply the third enclosure with cold via a circuit 274. Alternatively, the third cold source 272 can be arranged either in the outer enclosure or in the first cryogenic enclosure or the second cryogenic enclosure.

According to the embodiment shown in , at least a part, for example all, of the thermal locks 250 allows autonomous and independent access from outside the first cryogenic enclosure, for example from outside the outer enclosure, inside the third cryogenic chamber of a module comprising quantum chips.

In order to ensure a very low operating temperature for the quantum chips, the refrigeration system according to the invention comprises at least one sub-Kelvin refrigeration device 280. Each sub-Kelvin device makes it possible to produce a cold power so as to allow obtaining a temperature less than or equal to 1K, in particular less than or equal to a hundred milliKelvin.

As shown on the , at least part, preferably all, of the independent thermal locks allows access to a module comprising quantum chips from outside the first cryogenic enclosure to at least one of the sub-Kelvin refrigeration devices.

Typically, at least part, preferably all, of the sub-Kelvin refrigeration devices are arranged in the second, and/or for example the third, cryogenic enclosure.

According to one embodiment, some of the elements of the sub-Kelvin refrigeration devices 280 can be placed in the second cryogenic chamber 240 while another part of the elements of the sub-Kelvin refrigeration devices 280 are placed in the third cryogenic chamber 230 .

According to a configuration of a refrigeration system not shown in the figures, it is possible for at least one sub-Kelvin refrigeration device to produce cold power making it possible to obtain a temperature less than or equal to 1K at several modules comprising quantum chips.

As shown on the , according to one embodiment of the invention, each module comprising quantum chips also comprises at least one sub-Kelvin refrigeration device configured to produce cold power so as to make it possible to obtain a temperature lower than or equal to 1K, in particular less than or equal to a hundred milliKelvin. According to this embodiment, the sub-Kelvin refrigeration device is linked directly to the module comprising the quantum chips to be cooled. According to a possible variant, part of the modules comprise a sub-Kelvin refrigeration device while the remaining modules are cooled by sub-Kelvin refrigeration modules installed in the second or in the third cryogenic chamber.

All sub-Kelvin refrigeration devices making it possible to generate a cold power of at least 1 μW at a sub-Kelvin temperature can be used in the refrigeration system according to the invention.

According to an embodiment of the invention, at least one, for example all, of the sub-Kelvin refrigeration devices is a 3He refrigeration device. This type of refrigeration device is based on the principle of evaporative refrigeration. Reducing the pressure above a helium bath lowers the temperature of the helium bath. Thus, it is possible with the use of helium 3 to reach a temperature less than or equal to 1K, in particular less than or equal to a hundred milliKelvin.

According to an embodiment of the invention, at least one, for example all, of the sub-Kelvin refrigeration devices is an adiabatic demagnetization refrigeration device. This type of device is based on the entropy reduction of a paramagnetic material, for example by subjecting the paramagnetic material to an external magnetic field, followed by an adiabatic demagnetization, for example by removing the external magnetic field, allowing a reduction the temperature of the paramagnetic material. The choice of paramagnetic material makes it possible to reach very low temperatures. To reach a sub-Kelvin temperature, one can use alums whose magnetism is based on iron, chromium or cerium ions.

According to an embodiment of the invention, at least one, for example all, of the sub-Kelvin refrigeration devices is a dilution refrigeration device.

An example of a dilution refrigeration device is shown in .

The dilution refrigeration device shown in , comprises a working circuit 281 in a loop containing a cycle fluid comprising a mixture of isotope helium 3 (3He) and isotope helium 4 (4He). This working circuit 281 comprises, arranged in series and fluidically connected via a first set of

pipes

282, 284, a mixing chamber 283, a boiler 285 and a transfer member 286.

The first set of

pipes

282, 284 is configured to transfer cycle fluid from an outlet of the mixing chamber 283 to an inlet of the boiler 285 and from an outlet of the boiler 285 to an inlet of the transfer member 286 .

The working circuit 281 comprises a second set of pipes 287 connecting an output of the transfer unit 286 to an input of the mixing chamber 283.

The working circuit 281 comprises at least a first heat exchange portion 288 between at least a part of the

first pipe assembly

282, 284 and the second pipe assembly 287. The first heat exchange portion 288 is located between the boiler 285 and the mixing chamber 283.

The device further comprises at least one cooling member 289 in heat exchange with the working circuit 281 and configured to transfer cold temperatures to the cycle fluid, that is to say to cool the cycle fluid.

According to one embodiment of the invention, at least one, for example all, of the sub-Kelvin refrigeration devices may comprise at least one cryogenic pumping device located in its working circuit.

An example of this embodiment is shown in with a dilution refrigerator. As shown, the working circuit 281 of the dilution refrigerator may comprise a cryogenic pumping device 290 located between the boiler and the transfer device.

This cryogenic pumping device 290 can be configured to pump the fluid for example at a temperature greater than or equal to 0.5K, for example greater than or equal to 1.8 K, and less than or equal to 150K, for example less than or equal to 80 K. This cryogenic pumping device 290 comprises for example a pump of the turbomolecular type, or of the "Holweck" type for example, or with a centrifugal wheel or any other technology or combination of appropriate technologies.

This cryogenic pumping device 290 is configured to pump the fluid having a pressure greater than or equal to 0.01 mbar and less than or equal to 100 mbar. For example, the cryogenic pumping device 290 is configured to pump the fluid at approximately 0.1 mbar, and a low temperature, of the order of 700 to 850 mK, in accordance with the operation of the boiler 285. This cryogenic pumping device 290 is preferably configured to pump helium 3 having a pressure of about 0.1 mbar or less.

The presence of the cryogenic pumping unit 290 makes it possible to increase the flow rate of cycle fluid and therefore the cold power produced by the sub-Kelvin refrigeration device.

In an embodiment of the invention in which at least two of the sub-Kelvin refrigeration devices are refrigeration devices of the same nature, for example two dilution refrigeration devices or two ³ He refrigeration devices, it can be advantageous that these sub-Kelvin refrigeration devices share the same cryogenic pumping member.

According to a preferred embodiment of the invention, when at least one, for example all, of the sub-Kelvin refrigeration devices comprises a cryogenic pumping member, the pumping member is located inside the second cryogenic chamber and outside the third cryogenic chamber. Sub-Kelvin refrigeration devices can be located inside the third cryogenic chamber 270.

When the refrigeration device according to the invention comprises several sub-Kelvin refrigeration devices, these sub-Kelvin refrigeration devices can be configured to operate at different sub-Kelvin temperatures.

The invention has been described above with the aid of embodiments shown in the figures, without limiting the general inventive concept.

Thus, the doors can be opened successively according to an airlock operation (the first door is closed before the second is opened) or not (the first is left open and the second is opened).

In one possible embodiment, the second door is opened automatically (the opening of the second door is triggered by the opening of the first door, with or without delay).

In another possible embodiment, the second door is opened simultaneously with the first door (the two doors can be mechanically linked.

Thus, the opening of the first door allows the opening of the second door in the sense that the opening of the first door allows the opening of the second door either directly after the opening of the first door or after it was closed (and vice versa). Similarly, opening the first door gives access to the second door (and vice versa).

This system of two (or more) doors in series allows several possible uses/configurations, for example:

- direct access from the outside to the inside for loading and/or maintenance (therefore with vacuum breaking)

- access to the space between the doors for maintenance or loading at an intermediate temperature

- access via an airlock, so without breaking the vacuum inside.

Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

Especially,

although here the first wall and the second wall are straight cylinders with a polygonal base, the invention also applies to other types of wall such as curved walls from circular or any base cylinder;
although here the directing curve of the first cylinder is octagonal, the invention also applies to other types of polygonal directing curves such as for example a square, rectangular, hexagonal or any other curve;
although here the amounts have sections in the shape of a pentagon, the invention also applies to amounts of different section such as for example a triangular section;
although here the panels are flat, the invention also applies to other panel configurations such as curved or polyhedral panels;
although here the frames are attached by bolting, the invention also applies to other ways of removably mounting a panel on a frame such as, for example, screwing, clipping, magnetic fixing, a system with notches and tabs;
although here the associated frames and panels are rectangular, the invention also applies to other types of quadrangular frames and panels such as square or parallelogram-shaped frames and panels;
although here the panels are of quadrangular shape, the invention also applies to panels of different shapes, such as a triangular, circular or any shape;
although here the panels have a height equal to that of the enclosure, the invention also applies to panels of height less than that of the enclosure;
although here, the first end faces are fixed to the first frames, the invention also applies to other means of fixing an end face to an edge of the enclosure, such as fixing directly to the top edge of one or more panels;
although here the first enclosure is thermally connected to the second stage of a pulsed tube, the invention also applies to other types of first cold source, such as for example a stage of a dilution refrigerator, a cell Peltier or a gas expander or any other type of exchanger or cryogenic cooler (“cryocooler” in English);
although here the first external enclosure is thermally connected to the first stage of a pulsed tube, the invention also applies to other types of third cold source, such as for example a Peltier cell or a gas expander or any other type of cryogenic cooler (“cryocooler” in English)
although here a pipe crosses the upper face of the first enclosure, the invention also applies to other thermal connection members such as for example a thermally conductive metal braid. The connection can also be made on a lower end face of the first enclosure and/or of the second enclosure;
although here the second enclosure contains a dilution refrigeration device, the invention also applies to other types of sub-kelvin refrigerators, such as for example expansion refrigerators of the Joule-Thompson type (Helium 3 or Helium 4), Helium 3 refrigerators, or adiabatic demagnetization refrigerators;
although here the second enclosure and the first enclosure have identical structures, the invention also applies to enclosures of different structures such as for example a first enclosure with a hexagonal or square base and a second enclosure with a hexagonal or square base;
although here the first and second doors face each other, the invention also applies to other arrangements and configurations of the doors according to which the relative dimensions and positions allow the opening of the second door when the first door is opened;
although here the first and second airlocks have been described in connection with a polygonal structure of the first and second enclosure, the invention also applies to airlocks installed on other types of first and second enclosure such as example of cylindrical enclosures similar to those of the prior art;
although here the first door and the second door are connected by spring jacks, the invention also applies to other types of mechanical connecting members of the first door with the second door such as for example a block elastomer, a welded or screwed connection;
although here the doors are solid, the invention also applies to doors comprising passages for cables or passages for pipes intended to be connected to a device to be cooled placed in the second enclosure;
although here the doors include shelves projecting towards the inside of the enclosures, the invention also applies to other types of supports for receiving an element to be cooled, such as a pole or a hook;
although here the first and second outer enclosures have been represented in the form of two bolted half-cylinders, the invention also applies to other types of first and second outer enclosures, such as for example a first and a second outer enclosure comprising a polygonal frame and removable panels similar to the first and second enclosures;
although here the first and the second enclosure are under vacuum, the invention also applies to a system whose enclosures are not under vacuum or a system in which the first and the second enclosure share the same atmosphere under vacuum or each have their own vacuum, controlled separately using dedicated means. The first outer enclosure can also be under vacuum. The second outer enclosure can also be under vacuum. The first and second enclosures, as well as the first and second external enclosures can all share the same vacuum atmosphere, or they can each have their vacuum controlled separately. When all four enclosures share a single vacuum atmosphere, only the second outer enclosure is sealed;
although here the first wall and the second wall each comprise a single door, the invention also applies to walls comprising more than one door, the doors made in the first wall being substantially opposite those made in the second wall;
although here the panels are made of copper, the invention also applies to any other infrared blocking material such as for example brass, gilded copper, polished gilded copper, aluminum, or any other suitable material, having an emissivity coefficient greater than 0.8 and ideally as close as possible to 1.

Preferably, the doors are controlled to form an airlock: each door can only be opened when the other door is closed. It is possible to provide a mechanism making it possible, when the second door is open and the first door is closed, to transport a device to be cooled contained in the duct into the second enclosure and vice versa. The mechanism comprises for example a robotic arm contained in the second enclosure.

The above embodiments are given by way of example and are not intended to limit the scope of the invention, which is determined exclusively by the claims below.

In the claims, the word "comprising" does not exclude other elements or steps, and the use of the indefinite article "a" or "a" does not exclude a plurality. The mere fact that different features are listed in mutually dependent claims does not indicate that a combination of these features cannot be advantageously used. Finally, any reference used in the claims should not be interpreted as a limitation of the scope of the invention.

Claims

Refrigeration system (1) comprising:

a first cryogenic enclosure (10) defined by at least a first wall (11), the first cryogenic enclosure (10) being thermally connected to at least a first cold source (41);

a second cryogenic enclosure (50) defined by at least a second wall (51) which extends at least partially opposite the first wall (11), the second enclosure (50) being included inside the first enclosure ( 10) and thermally connected to at least one second cold source (43, 46);

characterized in that the refrigeration system (1) comprises at least a first door (30, 83) made in the first wall (11) substantially opposite a second door (70, 87) made in the second wall (51 ), the first door (30, 83) and the second door (70, 87) being arranged so that the opening of the first door (30, 83) allows the opening of the second door (70, 87 ), i.e. gives access to the second door.
A refrigeration system (1) according to claim 1, wherein the first door (30, 83) comprises a first frame (20, 82) on which a first panel (30, 83) is removably mounted, and wherein the second door (70, 87) includes a second frame (60, 86) to which a second panel (70) is removably mounted.
Refrigeration system (1) according to claim 2, in which the first enclosure (10) and/or the second enclosure (50) is a cylinder whose directing curve (12, 52) is polygonal, preferably octagonal, the first panel ( 30) being flat.
A refrigeration system (1) according to claim 3, wherein the first panel (30) defines a first side face of the first enclosure (10), the first panel (30) being quadrangular in shape and comprising a first width (11) corresponding to a length of a segment of the directing curve (12) and a first height (H1) which extends parallel to a generatrix of the cylinder.
Refrigeration system (1) according to any one of the preceding claims, comprising a third door (31-37) made in the first wall (11) and a fourth door (71-77) made in the second wall (51) substantially next to the third door (31-37).
Refrigeration system (1) according to claim 5, wherein the first door (83) and the second door (87) belong to a first airlock (80) and the third door (93) and the fourth door (97) belong to a second airlock (90), the first airlock (80) and the second airlock (90) being arranged to provide autonomous and independent access from the exterior of the first enclosure (10) to the interior of the second enclosure (50 ) respectively to a first module (100) and a second module (103) which both comprise a slot configured to receive at least one quantum chip (101, 104).
Refrigeration system (1) according to any one of the preceding claims, in which the first wall (11) and/or the second wall (51) comprises a material blocking the passage of infrared rays.
Refrigeration system (1) according to any one of the preceding claims, comprising mechanical connection members (110) of the first door (30) with the second door (70).
Refrigeration system (1) according to any one of the preceding claims, in which the first door (30) and/or the second door (70) comprises a support (120, 121) for receiving an element to be cooled.
Refrigeration system (1) according to any one of the preceding claims, in which the first cryogenic enclosure (10) comprises a first end face (39) through which extends a first heat transfer element (40) of the first cold source (41) and/or the second cryogenic chamber (50) comprises a second end face (59) and through which extends a second heat transfer element (42, 44, 45) of the second cold source (43,46).
Refrigeration system (1) according to any one of the preceding claims, in which the first cryogenic enclosure (10) is included in a first external enclosure (130).
Refrigeration system (1) according to claim 11, in which the first external enclosure (130) comprises a first additional door (160) arranged so that the opening of the first additional door (160) allows the opening of the first gate (30).
Refrigeration system (1) according to Claim 11 or 12, in which the first external enclosure is thermally connected to a third cold source.
Refrigeration system (1) according to Claim 13, in which the third cold source is configured to maintain a temperature of between forty Kelvins and one hundred Kelvins inside the first additional enclosure.
Refrigeration system (1) according to one of Claims 11 to 14, in which the first external enclosure (130) is included in a second external enclosure (140).
Refrigeration system (1) according to claims 12 and 15, in which the second external enclosure (140) comprises a second additional door (143) arranged so that the opening of the second additional door (143) allows the opening of the first additional door (160).
Refrigeration system (1) according to any one of the preceding claims, in which the first cold source (41) is configured to maintain a temperature of between 2.5 Kelvins and 5 Kelvins, preferably substantially equal to 4 Kelvins inside of the first enclosure (10), and the second cold source (43, 46) is configured to maintain a temperature of between 0.6 Kelvin and 1.5 Kelvin inside the second enclosure (50).
Refrigeration system (210) according to claim 1, arranged to receive independent modules (220) comprising quantum chips (222) operating at very low temperatures, in which:

the first cryogenic enclosure (230) and the first cold source (232) are configured to make it possible to maintain a temperature less than or equal to 150 K inside the first cryogenic enclosure (230),

the second cryogenic chamber (240) and the second cold source (242) are configured to make it possible to maintain a temperature less than or equal to 6 K inside the second cryogenic chamber (240),

a plurality of first doors and second doors form independent thermal locks (250) each allowing autonomous and independent access from the outside of the first cryogenic chamber (230) to the interior of the second cryogenic chamber (240) of a module (220) comprising quantum chips (222).
Refrigeration system according to Claim 18, in which the first cryogenic chamber (230) is thermally connected to the first cold source (232) by a circuit (234) able to transfer cold power from the said first cold source (232) to said first cryogenic chamber (230).
Refrigeration system according to claim 18 or 19, in which the second cryogenic enclosure (240) is thermally connected to the second cold source (242) by a circuit (244) able to transfer cold power from the said second cold source (242 ) to said second cryogenic enclosure (240).
Refrigeration system according to one of Claims 18 to 20, in which the first cryogenic chamber (230) is included in an external chamber (260) sealed at ambient temperature.
Refrigeration system according to claim 21, in which the set of enclosures sharing the same pressure less than or equal to 10 -4 mbar and greater than or equal to 10 -7 mbar and the thermal locks (250) each allowing autonomous and independent access from outside the outer enclosure.
Refrigeration system according to one of Claims 18 to 22, comprising a third cryogenic enclosure (270) included inside the second cryogenic enclosure (240) and thermally connected to at least a third cold source (272), the third cryogenic chamber (270) and the third cold source (272) being configured to make it possible to maintain a temperature less than or equal to 2 K inside the third cryogenic chamber (270), and at least part of the heat locks (250 ) allows autonomous and independent access from outside the first cryogenic enclosure (230) to the interior of the third cryogenic enclosure (270) of a module (220) comprising quantum chips (222).
Refrigeration system according to Claim 23, in which the third cryogenic chamber (270) is thermally connected to the third cold source (272) by a circuit (274) able to transfer cold power from the said third cold source (272) to said third cryogenic chamber (274).
Refrigeration system according to one of Claims 18 to 24, in which the thermal locks (250) are configured to receive from outside one of the cryogenic enclosures (230, 240, 270) modules (220) comprising quantum chips (222) and the links making it possible to communicate with said quantum chips (222).
Refrigeration system according to Claim 21, in which the thermal locks (250) are configured to receive from outside the external enclosure (260) modules (220) comprising quantum chips (222) and the links making it possible to communicate with said quantum chips (222).
Refrigeration system according to one of Claims 18 to 26, further comprising inter-module links making it possible to connect together quantum chips (222) of different modules (220).
Refrigeration system according to one of Claims 18 to 27, further comprising an anti-radioactivity protection device around at least one of the first and/or second and/or third cryogenic enclosures and/or the external enclosure , the anti-radioactivity protection device being configured to protect the interior of the refrigeration system from external radiation.
Refrigeration system according to one of Claims 18 to 28, comprising a plurality of sub-Kelvin refrigeration devices (280) arranged at least partly in the second cryogenic chamber (240), each sub-Kelvin refrigeration device (280) being configured to produce cold power so as to make it possible to obtain a temperature less than or equal to 1K, in particular less than or equal to a hundred milliKelvin.
Refrigeration system according to claim 29, in which at least one of the independent thermal locks (250) allows access to a module (220) comprising quantum chips (222) from outside the first cryogenic chamber (230) at least at least one of the sub-Kelvin refrigeration devices (280).
Refrigeration system according to one of claims 29 or 30, when dependent on claim 23, in which at least a part of the sub-Kelvin refrigeration devices (280) are arranged in the third cryogenic vessel (270).
Refrigeration system according to one of Claims 18 to 28, comprising at least one module (220) comprising quantum chips (222) and at least one sub-Kelvin refrigeration device (280) configured to produce cold power so to allow a temperature of less than or equal to 1K to be obtained, in particular less than or equal to a hundred milliKelvin, and at least one heat lock allowing access to said at least one module (220) from outside the first cryogenic enclosure (230) inside the second cryogenic enclosure (240).
A refrigeration system according to one of claims 29 to 32 wherein at least one of the sub-Kelvin refrigeration devices (280) is a 3 He refrigeration device.
Refrigeration system according to one of claims 29 to 33, wherein at least one of the sub-Kelvin refrigeration devices (280) is an adiabatic demagnetization refrigeration device.
A refrigeration system according to one of claims 29 to 34, wherein at least one of the sub-Kelvin refrigeration devices (280) is a dilution refrigeration device.
A refrigeration system according to claim 33 or 35, wherein the sub-Kelvin refrigeration device (280) includes at least one cryogenic pumping member (290) located in its working circuit (281).
A refrigeration system according to claim 36, wherein at least two of the sub-Kelvin refrigeration devices (280) are like-kind refrigeration devices and share a common cryogenic pumping member (290).
Refrigeration system according to one of Claims 36 or 37, when dependent on Claim 23, in which the cryogenic pumping member (290) is located inside the second cryogenic chamber (240) and outside of the third cryogenic chamber (270).
A refrigeration system according to claim 38, wherein the sub-Kelvin refrigeration device (280) is within the third cryogenic chamber (270).
A refrigeration system according to one of claims 29 to 34, wherein each sub-Kelvin refrigeration device (280) is configured to operate at different sub-Kelvin temperatures.